Measure twice and cut once! When I drilled my shelves (on a drill press which I know to be mandatory - it is nearly impossible to cut a perfectly perpendicular hole with a hand drill), I made a small jig out of thin aluminum, which guaranteed the position of the hole - just align it to the corner, and go. I think the most important aspect of cutting the hole is to use the right speed, and the right bit. As I said, I went 1/16" above the rod size to get a little play, and used a brand new forstner bit (most will state the correct speed for the material you are cutting), which gave me perfect cuts - no splinters or tearing of the grain at all.
My problem with most commercial products, and hence the impetus for building my own, was the near ubiquitous use of tubular material which rings like a bell. Who the hell wants to fill a rack with lead or sand? Commercially available racks in the price range we're looking (or building) at, are built to a price point, and are filled with compromise(s). There are many exceptions, but we begin to start talking serious cash. I also think it quite nice to be able to customize your dimensions, your choice of materials and finish, and to make the rack a customized unit that suits your needs. I also find great joy in building things myself - pride of workmanship, if you will. My rack seriously outperforms (sonically) everything I've heard under the $1000 mark (and of course I've not heard everything), but as a bang for the buck DIY project, I don't think you'll ever look back.
My problem with most commercial products, and hence the impetus for building my own, was the near ubiquitous use of tubular material which rings like a bell. Who the hell wants to fill a rack with lead or sand? Commercially available racks in the price range we're looking (or building) at, are built to a price point, and are filled with compromise(s). There are many exceptions, but we begin to start talking serious cash. I also think it quite nice to be able to customize your dimensions, your choice of materials and finish, and to make the rack a customized unit that suits your needs. I also find great joy in building things myself - pride of workmanship, if you will. My rack seriously outperforms (sonically) everything I've heard under the $1000 mark (and of course I've not heard everything), but as a bang for the buck DIY project, I don't think you'll ever look back.